Why do we sleep?

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Biscuit dunker

Original Poster:

91 posts

136 months

Tuesday 6th August 2013
quotequote all
Often thought about this.

I've read the stuff about why we need sleep from a biological point of view but never quite understood why we developed this need in the first place?

Do amoeba sleep?

Is it a fundamental requirement of all life-forms and if not, why did we develop the need in the first place?

Surely, applying Darwinian logic we'd have an advantage by never requiring sleep?

TwigtheWonderkid

44,717 posts

157 months

Tuesday 6th August 2013
quotequote all
I guess mayflies don't sleep. Bit of a waste of the day if they do.

Might not be an evolutionary advantage to stay awake. If it were, then slowly over millions of years, those that slept the least would have survived longer and mated more, passing on their insomniac genes, and by now we wouldn't sleep. So maybe those that slept the least lacked concentration when awake, or needed more food and couldn't find it, or the extra use of muscles and bone meant they didn't last as long.

As most species sleep, one can only assume sleeping gives an evolutionary advantage.

Different creature sleep different periods to suit. Cats can sleep for 19 hrs a day, some creatures are nocturnal, so evolution has given us the sleep arrangements that are best suited to our survival.

Simpo Two

87,127 posts

272 months

Tuesday 6th August 2013
quotequote all
Sleep must be essential or we wouldn't do it. I think it's because when awake the body uses up resources/fuel faster than they can be replenished, and sleep gives the processes time to catch up/unwind etc.

Hoofy

77,514 posts

289 months

Tuesday 6th August 2013
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Because it's nice.










biggrin

Biscuit dunker

Original Poster:

91 posts

136 months

Tuesday 6th August 2013
quotequote all
Hoofy said:
Because it's nice.










biggrin
x2.

But seriously, surely being able to stay awake and fully alert is an evolutionary advantage over needing to sleep to stay alert when awake?

jogon

2,971 posts

165 months

Tuesday 6th August 2013
quotequote all
Biscuit dunker said:
x2.

But seriously, surely being able to stay awake and fully alert is an evolutionary advantage over needing to sleep to stay alert when awake?
Having done a few weekenders during my uni days, fri-sun with the help of many chemicals, I can assure you it does not result in any evolutionary superpowers.

Quite the opposite, sleep is essential.

Biscuit dunker

Original Poster:

91 posts

136 months

Tuesday 6th August 2013
quotequote all
jogon said:
Biscuit dunker said:
x2.

But seriously, surely being able to stay awake and fully alert is an evolutionary advantage over needing to sleep to stay alert when awake?
Having done a few weekenders during my uni days, fri-sun with the help of many chemicals, I can assure you it does not result in any evolutionary superpowers.

Quite the opposite, sleep is essential.
Yes, but why have we developed this way? Surely eradicating sleep would be the prefered evolutionary direction?

Per my original question, do single cell critters need sleep? If not why do we and if so why didn't we evolve not to sleep? Always wondered about this one.

jogon

2,971 posts

165 months

Tuesday 6th August 2013
quotequote all
There was an article in the daily mail the other day that said if you spend a week camping in the great outdoors, by the end of the week your body clock will have reset it self, so you wake and sleep according to the sunrise/set.

http://www.dailymail.co.uk/health/article-2382569/...

I always wake up early, c5-6am, if I decide to lie in and doze off for a few hours then I always feel incredibly groggy.

So is there such thing as too much sleep?

Bisonhead

1,585 posts

196 months

Wednesday 7th August 2013
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We need to sleep to allow the body to heal, repair and regenerate...otherwise we would physically run ourselves down.

All mammals rest...some sleep as we do, others rest one half of their brain at a time. As mammals are highly active/use their bodies a lot there is need for a longer rest period.

I also understand that from a neurological point of view our brains need to rest in order to properly process the data it 'onboards' each day. In big-data studies it has been suggested that the average person will take on as much information in 1 day as someone 500 years ago would take on in their entire life! Pretty amazing really...I'm all sleepy now!

Simpo Two

87,127 posts

272 months

Wednesday 7th August 2013
quotequote all
Bisonhead said:
the average person will take on as much information in 1 day as someone 500 years ago would take on in their entire life!
Though to be fair 99% of it is ste, pointless or needless.

1513 sounds good smile

annodomini2

6,914 posts

258 months

Wednesday 7th August 2013
quotequote all
Combination of factors:

1. Healing as has been stated.
2. Memory reorganization.
3. Reduced energy usage (survival thing, basically we need less energy to exist)

There are probably more.

TwigtheWonderkid

44,717 posts

157 months

Wednesday 7th August 2013
quotequote all
Biscuit dunker said:
Yes, but why have we developed this way? Surely eradicating sleep would be the prefered evolutionary direction?

Per my original question, do single cell critters need sleep? If not why do we and if so why didn't we evolve not to sleep? Always wondered about this one.
Evolution is a process of compromises. Quite often advantages come with disadvantages. Flying is a huge advantage, but it also means hollow bones, massive chest muscles etc. Animals that fly can't run fast. To run fast you need powerful leg muscles and strong bones to anchor them to. If you want to run fast, give up flying, like an ostrich.

Maybe the advantages of being awake constantly comes with disadvantages like a bigger brain, thicker bones and muscles to take the extra usage. And these disadvantages outweighed the advantages, hence evolution took us down the sleeping route.

CaptainSensib1e

1,451 posts

228 months

Wednesday 7th August 2013
quotequote all
annodomini2 said:
Combination of factors:

1. Healing as has been stated.
2. Memory reorganization.
3. Reduced energy usage (survival thing, basically we need less energy to exist)

There are probably more.
Point 3 is a good one. Sleeping is a good way of conserving energy and before lights were invented you couldn't really achieve much when it was dark!

TheHeretic

73,668 posts

262 months

Wednesday 7th August 2013
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I think we slept because in the olden days nighttime TV was either rubbish, or non existent.

mu0n

2,348 posts

140 months

Wednesday 7th August 2013
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Biscuit dunker

Original Poster:

91 posts

136 months

Friday 9th August 2013
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Some good suggestions but doesn't really answer why.

Surely the optimum would be to not require sleep at all?

Dolphins don't sleep they just shut down bits of their brains. I'd have thought that by now we'd have 'evolved it out' of out makeup so we could go 24/7 (if you know what I mean..)

Simpo Two

87,127 posts

272 months

Friday 9th August 2013
quotequote all
Biscuit dunker said:
Some good suggestions but doesn't really answer why.
They do but you're ignoring them.

Ray Luxury-Yacht

8,914 posts

223 months

Friday 9th August 2013
quotequote all
As a biology and medical student (with a bit of mental and physical psychology chucked in), I have studied this a bit - and after doing a fair bit of research, the simple answer is this:

Human sleep is basically for the brain only.

Yes, I agree that there are physiological repairs and maintenance that also occur within the rest of the body during sleep too - but mainly because the conditions are favourable to do so during sleep - i.e. lack of movement, low energy demands etc...

But most human biologists agree that the physical body would be fine to be awake and moving constantly, without sleep (but not necessarily without some rest, obviously). It would just mean that the usual repairs and maintenance within the body's systems would occur a little slower than with sleep.

Sleep appears to allow our complex brains to re-organize, re-boot and congnitively prepare for the next period of wakeful exposure. The difference between us and other mammals that don't necessarily sleep for as long as we do, or sleep in part is that our brains are the only ones on the planet that have cognitive consciousness and the ability to be self-aware and make decisions involving many complex factual and emotional reasoning.

No other living things do so, obviously.

If you have a Google around, there are lots of studies and experiments into sleep factors, and how lack of it affects our cognitive ablility - plus explainations about how the rest of our bodies could function without it.




Art0ir

9,406 posts

177 months

Friday 9th August 2013
quotequote all
Ray Luxury-Yacht said:
As a biology and medical student (with a bit of mental and physical psychology chucked in), I have studied this a bit - and after doing a fair bit of research, the simple answer is this:

Human sleep is basically for the brain only.

Yes, I agree that there are physiological repairs and maintenance that also occur within the rest of the body during sleep too - but mainly because the conditions are favourable to do so during sleep - i.e. lack of movement, low energy demands etc...

But most human biologists agree that the physical body would be fine to be awake and moving constantly, without sleep (but not necessarily without some rest, obviously). It would just mean that the usual repairs and maintenance within the body's systems would occur a little slower than with sleep.

Sleep appears to allow our complex brains to re-organize, re-boot and congnitively prepare for the next period of wakeful exposure. The difference between us and other mammals that don't necessarily sleep for as long as we do, or sleep in part is that our brains are the only ones on the planet that have cognitive consciousness and the ability to be self-aware and make decisions involving many complex factual and emotional reasoning.

No other living things do so, obviously.

If you have a Google around, there are lots of studies and experiments into sleep factors, and how lack of it affects our cognitive ablility - plus explainations about how the rest of our bodies could function without it.
Did you ever read into the training yourself to skip the "useless" bits of sleep? I think it's the Sony CEO that only sleeps 2 or 3 hours a night because he goes straight to REM (?)

aw51 121565

4,771 posts

240 months

Saturday 10th August 2013
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Art0ir said:
he goes straight to REM (?)
If he does, he's a lucky - infinitely superhuman and utterly blessed - man cloud9 ; most of us only enter REM on average an hour or so after shuteye, generally? confused. 8 hours good kip = 6ish hours proper deep REM sleep, or similar? (again confused ).

The rest of us busk it when the going gets quiet - and hope no-one notices the sleep moments redface - we generally get away with it, busking along the libne of "sorry, can you repeat that?"" on a regular basis! wink ) ...